1. Technical Field
The present invention relates to a pretreatment agent for ink jet ink. The pretreatment agent according to the invention is used in combination with the ink jet ink containing an acid dye, thereby reducing smearing and allowing a high-quality image having a high coloring property to be obtained.
2. Related Art
In the related art, examples of a method of printing an image onto cloth includes a screen printing method, a roller printing method, a rotary screen printing method, and a transfer printing method. However, since it is necessary to prepare an expensive screen frame, an engraving roller, or a transfer paper for every change in image design in the methods, the methods are not suitable for limited production of diverse products in terms of cost and cannot cope with diversification of fashion quickly.
To solve the problem of the known printing methods, a technology has been developed in which a sample copy is read by a scanner, image processing is performed by a computer, and the resultant image is printed using an ink jet printing method. However, since the ink jet printing method has been developed as a technology using paper as a recording medium, smearing was marked and vividness was deteriorated. The reason is that since cloth has a fiber structure or a fabric structure having directionality and voids larger than those of paper, ink smears into the cloth in longitudinal and horizontal directions, whereby it is difficult to obtain a vivid image. For the ink jet printing method, since ink droplets are ejected from an ink head to the recording medium, it is theoretically impossible to just apply high-viscosity ink used in the known printing method and it is necessary to reduce a viscosity to a considerable low level to prevent the ink head from becoming clogged.
Therefore, for an ink jet printing method, a technology has been developed in which, as a printing paste used in the known printing method, a printing paste having two constituents such as a high-viscosity pretreatment agent and low-viscosity ink is used, the cloth being first subjected to padding processing with the pretreatment agent, and then ink being ejected from a printer head to the pretreated cloth. For an ink jet printing method, a technology has been also proposed of which an object is to prevent smearing by providing a particular constituent in the treatment agent, thereby allowing a vivid image to be obtained.
For example, in JP-B-63-31594, an ink jet printing method is proposed in which smearing is prevented using a pretreated cloth previously treated with a dye holding agent, thereby enabling a vivid image to be obtained. JP-B-63-31594 discloses that the dye holding agent includes a water-soluble polymer (i.e., a natural water-soluble polymer or a synthetic water-soluble polymer), water-soluble salt, and a water-insoluble inorganic particle. However, JP-A-10-183481 discloses that since large fluctuations in coloring occur due to differences between batches of a cloth material and differences in temperature-humidity conditions between storage locations or processing sites for industrial production, there is a problem with color reproducibility and since uneven dyeing occurs, there is a problem in obtaining a constant dying property in the method disclosed in JP-B-63-31594.
The present inventor has studied a pretreatment agent capable of being used to obtain a vivid image to be obtained by preventing smearing and achieving a high coloring property and has found that a smearing-resistant effect is markedly improved, thereby enabling a very vivid high-quality image having a high coloring property to be obtained by using hydroxyethyl cellulose as a water-soluble resin constituent to be obtained.
However, that incorporation of a water-soluble polymer compound such as hydroxyethyl cellulose into a pretreatment agent has already been proposed in the past. For example, in JP-B-63-31594, a dye holding agent incorporated into the pretreatment agent includes a natural water-soluble polymer such as a water-soluble polymer (i.e., a natural water-soluble polymer or a synthetic water-soluble polymer), water-soluble salt, and a water-insoluble inorganic particle, and more specifically, includes starch (from a sweet potato, a potato, corn, or wheat), a cellulose substance (carboxyethyl cellulose, methyl cellulose, or hydroxyethyl cellulose), polyssccharide (sodium alginate, gum arabic, locust bean gum, tragacanth gum, guar gum, or a tamarind seed), a protein substance (gelatine or casein), or a tannine series substance, a synthetic water-soluble polymer such as a polyvinyl alcohol series compound, a polyethylene oxide series compound, an acrylate water-soluble polymer, or a maleic anhydride series water-soluble polymer), water-soluble salt such as an alkali metal (NaCl, Na2SO4, KCl, CH3COONa) or an alkali earth metal (CaCl2 or MgCl2), a water-soluble inorganic particle (ZnO, SiO2, CaCO3, BaSO4, TiO2, Al(OH)3, Fe2O2, CaO, K2O, or silicate aluminum salt), or a natural clay substance (bentonite, diatom earth, activated earth, kaolin, talc, or montmorillonite). In other words, hydroxyethyl cellulose is exemplified as one example of a cellulose series substance incorporated into the natural water-soluble polymer in JP-B-63-31594.
However, in embodiments of JP-B-63-31594, an aspect in which polyvinyl alcohol (the synthetic water-soluble polymer), CaCl2 (an alkali earth metal), and bentonite (natural clay substance) are used as the dye holding agent for an acid dye is specifically disclosed, but an aspect in which the natural water-soluble polymer (for example, the cellulose series substance or the protein substance) is used as the dye holding agent for the acid dye is not specifically disclosed. Even in a comparative example, an aspect in which gelatine (the protein substance) is used as the dye holding agent for the acid dye is just disclosed. It is just disclosed that gum arabic (polysaccharide), NaCl (the alkali metal), and montmorillonite (the natural clay substance) are used as the dye holding agent for a disperse dye. In other words, in JP-B-63-31594, since a specific aspect employing the cellulose substance is not disclosed, a specific examination is not performed. In JP-B-63-31594, it is specifically disclosed that gelatine (the protein substance) incorporated into the natural water-soluble polymer compound is used as a comparative substance and is inferior in coloring property.
In contrast, as specifically described in embodiments to be described later, it is possible to obtain a high-quality image having a high coloring property without occurrence of smearing in comparison with polyvinyl alcohol, CaCl2, and bentonite specifically examined in the above-mentioned embodiments of JP-B-63-31594 by using hydroxyethyl cellulose. In other words, it is possible to realize a high coloring property exceeding a limit of the coloring property in the known ink jet printing method with marked reduction (i.e., realization of a very vivid image) in occurrence of smearing by using hydroxyethyl cellulose. Hydroxyethyl cellulose is superior for obtaining a high-quality image to other representative water-soluble resin constituents such as sodium alginate or guar gum. Hydroxyethyl cellulose is superior for obtaining a high-quality image even to other cellulose substance (i.e., carboxymetyl cellulose).